U.S. Pat. No. 3,566,662 describes disposable sleeves for coldworking of holes. The apparatus uses a tapered oversized plug element with a thereon positioned thin-walled split sleeve. The plug element is inserted with the sleeve into a hole. When the plug element is pulled back through the hole, the sleeve is kept in the hole by the apparatus so that radially outwards directed forces are exerted by the plug on the sleeve, which in turn transmits the coldworking forces to the wall of the hole. After the plug is pulled out of the hole, the sleeve is removed from the hole and discarded.
U.S. Pat. No. 4,566,662 describes coldworking of holes using a split mandrel. The apparatus uses a mandrel having radially directed slots to permit contraction of its outer diameter as it is fitted within a hole. The mandrel contains a pilot inside the mandrel. After placing the mandrel and pilot within a hole to be coldworked, the pilot is pushed into the mandrel expanding the mandrel. The pilot and mandrel are then withdrawn through the hole, thereby coldworking the hole.
U.S. Pat. No. 5,943,898 describes coldworking holes using a pre-lubricated tubular seamless sleeve made of shape memory alloys. The apparatus uses a pre-lubricated tubular seamless sleeve made of shape memory alloys, a mandrel having a larger diameter end, a nose cap with rough conical surface, and a spacer with rough complementary conical surface. The mandrel retracts backwardly through and out of the sleeve; thereby expanding the sleeve wall against the hole wall and exerts radially outward forces on the sleeve. Which in turn transmits the coldworking forces to the hole wall. After the mandrel is pulled out of the hole, the sleeve diameter restores to its original diameter because of the superelastic property of shape memory alloys, and therefore it can be easily removed out of the hole.
These coldworking methods and systems result in substantial axial plastic flow of metal to the mandrel-exit side of a metal sheet.